See the umx and OpenMx home pages for more.

 - (\url{https://github.com/tbates/umx})
  - (\url{https://openmx.ssri.psu.edu})

Note: In addition to the version of OpenMx on CRAN, a version with
NPSOL-enabled is available. To install it, once you have umx installed run

install.OpenMx("NPSOL")